I saw a circuit of a galena radio that uses a transformer with a high input impedance to power a speaker. It works?"
Evidently, galena radios are not the best for feeding loudspeakers, as they depend entirely on the energy captured by the antenna, which is not the largest. However, if the signal is strong in your area, you can use a loudspeaker, but with an additional transformer. The purpose of the loudspeaker in this case will be to match the high impedance of the radio circuit with the low impedance of the loudspeaker. An output transformer with 500 ohms at 2k of primary taken from an old transistor radio works, but it is much better to find an output transformer from a tube radio with more than 10,000 ohms of primary.
